Know that Lara can move forward to spawn enemies, then retreat to a safe spot (the alley where the Marksmanship Medal is found is a good place) to draw enemies to her. Shooting enemies will almost never follow charging enemies (the ones who melee), so you can separate the enemy's forces and kill them piece-meal (divide and conquer).

Defeat all the enemies (including detonating the tower with red explosive barrels) and use that tower base as a "base of fire" to plink the rest of the skirmishers. Once Lara approaches the comm tower building's doors, the shield enemy will appear.

Lara will earn Axe Strikes and can use the pry axe to do some home-made brain surgery on the shield enemy. Dodge his attack, then counterattack by pressing Lara's shove button (which will now let her swing the Pry Axe like some crazy hatchet-wielding pro-Temperance harpy). Smash his little face in and loot the corpses of everyone. Note that the "weapon part" may be found in a variety of ways (including salvage boxes later), but this Bow Part is from the shield foe.

The Base Exterior Treasure Map is on the center "dais" (for lack of a better term), There is that is reachable only by zip-line from the area's local base camp.

While you are here, You are gonna want to clear out the shield soldier from the fortress, and then pacify the interior. Once that's done, you may have Lara freely explore the grounds (and the zip line from the base camp) without further incident. And for no damage uphead.

Lara zips down to the fuel tank on the mountain top. She will find the Firestriker and will be able to light her torch anywhere. Use the torch to set the fuel on fire. After the cut-scene, she will be on the Cliffside Village.